In its 1974 Lau v. Nichols decision, the U.S. Supreme Court stated that public schools have an obligation to provide appropriate language services to students who are learning English. As a result, today when a student enters public school for the first time in the United States, be it in kindergarten or at a point during high school, his or her need for English language services is evaluated. (In most states, students' proficiency in non-English languages is never screened or evaluated—Minnesota is a notable exception).

Nationally, there are standard practices for identifying, monitoring, and exiting dual language learners (DLLs) or English language learners (ELLs) from English as a Second Language (ESL) services. While many preschool programs also screen for language proficiency, there is substantial variability in states' screening policies and programs' use of these instruments; the standard practices outlined are specific to kindergarten through 12th grade.

Time it Takes to Learn English

The legal obligation to provide language services has prompted considerable interest from policymakers who want to know: how long does it take for DLLs to learn English? There is not, however, a clear-cut answer.


The first step in determining a student's need for language services is through a home language survey. This simple screen asks parents what languages their child speaks.


Once a child has been identified as an ELL, schools are required to monitor his or her English development through an annual assessment. Moreover, federal law requires schools to assure that ELLs gain proficiency within a "reasonable" amount of time.

Exit From Services

An ELL cannot be officially exited from language services until they have demonstrated proficiency in reading, writing, speaking, and understanding English. At this point, the student is no longer be considered an ELL and will be exited from services.